The present invention relates to an apparatus for inserting a deformable or foldable lens into an eye. More particularly, the invention relates to such an apparatus constructed so as to fold the intraocular lens and to be proximally loaded with the intraocular lens to be inserted.
An intraocular lens (IOL) is implanted in the eye, for example, as a replacement for the natural crystalline lens after cataract surgery or to alter the optical properties of (provide vision correction to) an eye in which the natural lens remains. IOLs often include an optic, and preferably at least one flexible fixation member or haptic that extends from the optic and becomes affixed in the eye to secure the lens in position. The optic normally includes an optically clear lens. Implantation of such IOLs into the eye involves making an incision in the eye. It is advantageous, to reduce trauma and speed healing, to have the incision sized as small as possible.
IOLs are known which are foldable (deformable) so that the IOL can be inserted through a smaller incision into the eye. A substantial number of instruments have been proposed to aid in inserting such a foldable lens in the eye. Many of these instruments involve pre-folding the lens before the lens is placed in the insertion device. While this hand folding allows the lens to be inserted through a relatively small incision, it is time consuming and the added handling can damage the lens.
Many of the prior art IOL insertion systems load and/or fold the IOL at the distal end, that is at the end closest to the eye or the end inserted into the eye. Such "distal loading" systems often disadvantageously include a space consuming loading component at or near the distal end of the system which causes the distal end to be relatively large. This relatively large distal end makes inserting the IOL through a small incision more difficult, if not impossible. Also, the IOL itself may structurally compromise the distal end of the inserter as a result of the distal end loading operation. Systems which fold and load the IOL proximally of the distal end provide certain advantages, such as reduced stress on the IOL and/or inserter, relative to "distal loading" systems.
Mazzocco U.S. Pat. No. 4,573,998 discloses a number of IOL insertion devices. One of these, in which the IOL is loaded proximally, provides that the unfolded IOL is maintained in a suitable liquid medium in a chamber integral with the insertion tube. Fluid pressure is used to cause the unfolded IOL to pass from the chamber into the insertion tube or cannula and then into the eye. Using fluid pressure to move the IOL from the chamber through the cannula into the eye can result in exposing the eye to relatively high fluid pressures which can damage the eye. The construction of this device, particularly proximally of the chamber, makes folding the IOL in the chamber by mechanical means, such as by using forceps, very difficult, if not impossible.